Hippert / Geissler / Hodeau Neutron and X-ray Spectroscopy

1. Auflage 2006
ISBN: 978-1-4020-3337-7
Verlag: Springer Netherland
Format: PDF
Kopierschutz: 1 - PDF Watermark

E-Book, Englisch, 591 Seiten, eBook

Neutron and X-Ray Spectroscopy delivers an up-to-date account of the principles and practice of inelastic and spectroscopic methods available at neutron and synchrotron sources, including recent developments. The chapters are based on a course of lectures and practicals (the HERCULES course at the European Synchrotron Radiation Facility) delivered to young scientists who require these methods in their professional careers. Each chapter, written by a leading specialist in the field, introduces the basic concepts of the technique and provides an overview of recent work. This volume, which focuses on spectroscopic techniques in synchrotron radiation and inelastic neutron scattering, will be a primary source of information for physicists, chemists and materials scientists who wish to acquire a basic understanding of these techniques and to discover the possibilities offered by them. Emphasizing the complementarity of the neutron and X-ray methods, this tutorial will also be invaluable to scientists already working in neighboring fields who seek to extend their knowledge.

Zielgruppe

Research

Autoren/Hrsg.

Hippert, Françoise

Geissler, Erik

Hodeau, Jean Louis

Lelièvre-Berna, Eddy

Regnard, Jean-René

Inhaltsverzeichnis

X-ray Spectroscopy.- Fundamentals of X-ray Absorption and Dichroism: The Multiplet Approach.- Multiple Scattering Theory Applied to X-Ray Absorption Near-Edge Structure.- X-ray Magnetic Circular Dichroism.- Extended X-Ray Absorption Fine Structure.- Inelastic X-Ray Scattering from Collective Atom Dynamics.- Photoelectron Spectroscopy.- Anomalous Scattering and Diffraction Anomalous Fine Structure.- Soft X-Ray Photoelectron Emission-Microscopy (X-PEEM).- X-Ray Intensity Fluctuation Spectroscopy.- Vibrational Spectroscopy at Surfaces and Interfaces Using Synchrotron Sources and Free Electron Lasers.- Neutron Spectroscopy.- Inelastic Neutron Scattering: Introduction.- Three-Axis Inelastic Neutron Scattering.- Neutron Spin Echo Spectroscopy.- Time-of-Flight Inelastic Scattering.- Neutron Backscattering Spectroscopy.- Neutron Inelastic Scattering and Molecular Modelling.

Leseproben

6 PHOTOELECTRON SPECTROSCOPY (p. 189-190)

M. GRIONI
Institut de Physique des Nanostructures,
Ecole Polytechnique Fédérale de Lausanne, Switzerland

1. INTRODUCTION

Most properties of materials reflect, directly or indirectly, the nature of their electronic states. Electrons interact with the ions – and therefore feel the translation symmetry of the lattice – but also, namely in interesting materials, with other electrons. This leads to complex correlated states. Not surprisingly, the most straightforward way to investigate electronic properties is to remove the electrons from the solid, and to measure them far from the interacting system. This is the general idea of a photoemission experiment. Perhaps more surprisingly, such a simple measurement contains crucial information on the interacting system. The purpose of this chapter is to illustrate this simple and powerful idea.

The impressive results obtained over the past four decades, and the huge number of experiments performed every year, demonstrate that photoemission has reached the venerable status of a standard probe of the electronic properties of solids. And yet, new and exciting developments, often associated with synchrotron radiation, are reshaping the practice and scope of the technique, bridging the gap with conventional "thermodynamic" probes of the electronic states. The forefront of research has moved from studies of the band structure on the eV scale, to the investigation of elementary excitations, electronic instabilities, and new exotic properties of correlated systems, at the meV range and with high momentum resolution. In this perspective, this chapter gives only a very brief account of traditional aspects of photoelectron spectroscopy, while it addresses, with examples from the recent literature, the spectral properties of correlated electron systems. For a broader view and a much more detailed description of the technique the reader is referred to some excellent reviews.

This chapter is organized as follows: section 2 gives a brief qualitative description and an intuitive interpretation of a photoemission experiment. Section 3 presents a discussion of a photoemission spectrum based on the simple and widespread 3-step model. Correlation effects and their manifestation in the spectral properties are introduced in section 4. These ideas are illustrated by selected case studies in section 5.

2. WHAT IS PHOTOEMISSION?

Photoelectron spectroscopy (PES) is a photon in-electron out experiment (figure 1). The interaction of a monochromatic beam of UV or soft X-ray photons with a sample generates photoelectrons with a broad distribution of emission angles and kinetic energies. The target may be indifferently a solid, a liquid or a gas, but in the following we will implicitly consider the more common case of a solid. The emitted electrons are then collected over a broad (angle-integrated PES, or simply PES) or a narrow (angle resolved PES or ARPES) acceptance angle. The subsequent measurement of the distribution of kinetic energies, typically performed by an electrostatic analyzer, yields a spectrum or energy distribution curve (EDC). The EDC represents the number of photoelectrons measured as a function of kinetic energy within the energy and angular acceptance windows of the analyzer. The measured intensity depends in a non-trivial way on various parameters that can be controlled, at least in principle, independently. They include the energy, polarization and incidence angle of the photon beam, the orientation and temperature (and magnetization etc.) of the sample, the collection angle and the angular acceptance window of the analyzer. A measurement of the spin may be added to the energy analysis, but the specific topic of spin-resolved PES and ARPES, which is of obvious interest in the study of magnetic systems, will not be covered here.